MapReduce's use of input files and lack of schema support prevents the performance improvements enabled by common database system features such as B-trees and hash …

Feb 3, 2019 · Compared to MapReduce, which creates a DAG with two predefined stages - Map and Reduce, DAGs created by Spark can contain any number of stages. DAG is a strict …

Dec 10, 2015 · mapreduce.shuffle.max.threads: Number of worker threads for copying the map outputs to reducers. mapreduce.reduce.shuffle.input.buffer.percent: How much of heap should …

Aug 26, 2008 · MapReduce is a method to process vast sums of data in parallel without requiring the developer to write any code other than the mapper and reduce functions. The map function …

Jul 31, 2011 · For each input split a map task is spawned. So, over the lifetime of a mapreduce job the number of map tasks is equal to the number of input splits. mapred.map.tasks is just a …

What scenarios would warrant the use of the "Map and Reduce" algorithm? Is there a .NET implementation of this algorithm?

I am getting: FAILED: Execution Error, return code 2 from org.apache.hadoop.hive.ql.exec.MapRedTask While trying to make a copy of a partitioned …

Sep 25, 2013 · If you are using Hadoop Streaming, you can use the JobConf variables in a streaming job's mapper/reducer. As for the input file name of mapper, see the Configured …

Mar 3, 2014 · Then, the MapReduce job stops at the map phase, and the map phase does not include any kind of sorting (so even the map phase is faster). Tom White has been an Apache …

Aug 23, 2013 · Can any one explain me how secondary sorting works in hadoop ? Why must one use GroupingComparator and how does it work in hadoop ? I was going through the link given …